Method of impression-taking in relining dentures



Nov. 11, 1952 B, D. RANDALL 2,617,193

METHOD OF IMPRESSION-TAKING IN RELINING DENTURES Filed April 28, 1950 2SHEETS-SHEET 2 Inventor; fierzno fi. fiarzdzZZ, y 7% 27 Patented Nov.11, 1952 UNITED STATES PATENT or fice];

METHOD OF IMPRESSION-TAKING IN RELINING DENTURES Benno D. Randall,Boston, Mass.

Application April 28, 1950, Serial No. 158,888

1 Claim. 1

This invention relates to a method of relining artificial dentures, andpertains more particularly to an improved method or technique; ofimpression-taking in the process of relining or rebasing full lowerdentures.

As is well understood .by the dental profession, the relining of full,lower, artificial dentures is necessary in most instances, at variableperiods of time following the original insertion of the denture, becauseof progressive atrophic changes which take place in the mandible onwhich the denture rests. Due to such atrophy, stability of the dentureis lost, discomfort to the wearer increases, and speech and masticationare-impaired. In order to overcome these conditions, it is necessary toreline the denture to conform to the new anatomy of the mandible, or toconstruct a new denture.

Heretofore, the conventional method of impression-taking for relining afull lower denture has involved placing an impression medium in thegroove of the denture which rests on the gum tissues over the mandible,without changing the form of the denture or otherwise preparing it forthe reception of the impression material; inserting the denture (filledwith the impression material) into the patients mouth, in its normalposition; having the patient close the mouth and hold the denture inposition bypressure from the upper teeth, so that the impressionmaterial conforms to the shape of the mandible; and removing the dentureafter the material has hardened. This technique is known to theprofession as the pressure method of impression-taking.

The use of the pressure method has several unsatisfactory results. Forexample, pressure on the filled denture forces the soft and removablegum tissues away from their normal rest positions over the mandible, andthe tissues will thus be forced to abnormal positions when the reliningis used; and such unnatural pressure, applied to a mandible uncushionedby gum tissues, causes more rapid bone atrophy and thus requires morefrequent relining of the denture and causes eventual attrition of thealveolar ridge of the mandible, until the patient is no longer able touse a lower denture efficiently or comfortably. Moreover, the relineddenture is unduly thickened, resulting in the destruction of the correctfacial and bite distances which were carefully restored by the originaldenture, and immediately afiecting the physical and mental comfort ofthe wearer.

It is, therefore, the principal'purpose of the present invention toeliminate the unfavorable results of the conventional pressure method of2 i impression-taking for the purpose of .relining lower dentures, byproviding an improved technique which obviates-the tissue-distortingpressures discussed above, and also avoids unnecessary or excessivethickening of the denture. The improved method, which may be termed anone pressure impression technique, obtains a true impression of thesoft and movable gum tissues,'in' their normal or rest positions, overthe mandible, and retains the restored facial and bite distances of theoriginal denture.

More specifically, it is an object of this invention to achieve thesedesirable results by so preparing the lower dentures, before theapplication of the impression material thereto, that the denture willhold an adequate quantity of the material in a plastic state, and willpermit the plastic material to flow under very gentle pressure andconform to the gum tissues without distorting or displacing them fromtheir normalv positions.

This preparation involves the removal of a substantial portion of sideribs or flanges of the denture, and a lesser portion of the bottom ofthe groove between the flangeawhileleaying contact spots or stops of theoriginal denture. The stops are preferably provided at the respectiveretromolar triangles or pads, and at-the'bottom of the original denturegroove at opposite sides of the cuspid area, so that the prepareddenture may be accuratelyrefitted to-the'patientsmouth during the takingof th impression.

After the artificial denture has been prepared and the impression hasbeen taken in accordance with this invention, a model of the hardenedimpression material is poured and invested, and the liner of denturematerialis prepared and bonded to the denture case in accordance withcommon practice.

The novel technique in the preparation of a lower denture, in accordancewith this invention, is illustrated in the accompanying drawings, inwhich:

Fig. 1 is a plan view of the grooved or gum tissue side of the lowerdenture which is to be relined;

Fig. 2 is a section on line 22 of Fig. 1;

Fig. 3 is a view similar to Fig. 1, after portions of the denture havebeen removed to leave the contacts or stops herein described, inpreparing the denture for impression taking;

Fig. 4 is a section on line 4-4 of Fig. 3;

Fig. 5 is a diagrammatic side view, partly broken away and in section,showing the prepared denture fitted to the lower jaw, with impressionmaterial between the denture and the gum;

Fig. 6 is a section on line 6-6 of Fig. 5;

Fig. 7 is a side view of a plastic model made from the original denture,before preparation or treatment, with the denture applied thereto; and

Fig. 8 is a view similar to Fig. 7, showing the prepared denture appliedto the model.

As illustrated in the drawings, the improved denture rebasing method isdevised to provide a relining for afull lower denture II which haspreviously been preparedand fittedto a patients mouth, and worn for aperiod of time. The

denture has an arcuate groove 12 which receives the tissue-coveredalveolar ridge of the mandible,

and peripheral margins or flanges l3i 'which' ex-e' tend along thelingual and buccal areas," on op posite sides of the groove I2, toembrace the ridge. The retromolar triangles or pads are indicated at M.

In accordance with this invention, before tak: ing the new impressionfor the purpose of making a liner for the case II, the flanges I3 and aportion of the bottom of the groove-I Z'are ground away to remove mostof fthesurface which normally contacts the-soft, movable gum tissues,-while leaving; intact the retromolar padsl4- and two contactpointsorstops I5 -at-the opposite sides of the cuspidarea intact. The removedportions are 'indicated by broken lines'in Fig: 4, the denture materialatth'e bottomof thegroove l2 'being removed-to a depth of not more than2mm. Thus, the opposite flanges l3 are totally removed and only fourpoints or spots of the original gum-contacting surfaces of "the dentureare left intact, namely, the retromolar pads 14 and the cuspid stopsl5."

Before the denture is thus prepared, dental plaster or artificial stoneis poured into the groove I2 or gum tissue sideof the original denture,toproduce amale model,- representing thepatients lower gums, asindicated at l9 in Figs. 7 and 8. The denture is "removed from thehardened model "and thefour-stop-areas l4; l4 and l5, 15 aresuitablymarked in outline on the gum tissue side-of the denture.Theremaining surfaces of the-gum tissue side of the denture, andthe-entire fiangedperipherythereof, are reduced or removedb'y-grinding,- (mother-- wise, ,as aforesaid, to thenew surface l1.

During the grinding operation-, the denture H maybe replacedon=-the-model I9-'from time to time, with thefour stopscontactingtheridge of the model, to determinewhether the reduced areashave-beensufliciently removed so that the remaining surf aces are out ofcontact with the model (Fig. 8).- The'spacing-shouldbe approximately twomillimeters. Thus the denture may be accurately reduced in preparationfor impressiontaking; at the dental laboratory 1 without repeatedfittings to the patients mouth. A final fitting to the mouth is desiredhowever, before the impression material is applied to the prepareddenture; and any imperfections are corrected by the dentist.

Suitable impression material (6 is then poured onto the prepared surfaceof the denture, and the dentureis placed in the patients mouth to takethe non-pressure impression. The denture is floated down with lightpressure to its proper position over the mandible 18, as determined bythe four location stops which lightly contactthesofttissues. The patientthen gently closes the mouth and maintains light pressure on the dentureuntil the material sets. The light pressure is exerted on the gum onlyat the four contact areas; :there is little or no pressure on theplastic impression material l6 which freely flows-between the reducedsurface I! and the gum tissues, without displacing the movabletissuesfrom their-normal rest positions.

When. the impression-material has set, the denture isremoved from thepatients mouth, another'model is poured and invested, and the denture isrelined or rebasedin accordance with accepted laboratory procedure.

The preparationot'the denture prior to impression-taking providesarebased denture which will fit accurately and comfortably in thepatients mouth, without distorting the soft gum tissues, andwhichwilleliminate rapid atrophic changes in' the'mandibleand henceobviate frequent relining of the denture.

I claim:

A method"ofimpression-taking' for relining lower dentures which consistsin removing substanti'al portions of the'gum-contacting surfaces of thedenture, while leaving intact a plurality of relativelysmall', spaced,gum-contacting supports at 1 the respective retromolar and cuspid areas,applying plastic impression material to the denture, and: takinganon-pressure impression in the mouth of the patient while theimpression material is plastic'and free-flowing.

BENNO D. RANDALL;

REFERENCESLCITED The'following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,887,749 Bowers Nov. 15, 19322,036,715 Morgan Apr. '7, 1936 2,165,597" Widoe, Sr. July 11, 19392,466,727" Morgan Apr. 12, 1949

